Method of making plastic molds

Abstract

An improved method for forming plastic molds for casting articles having an optical surface such as contact lenses employs a plastic tool having an optically smooth surface.

We claim: 
     
       1. In a process for forming plastic molds having an optically smooth molding surface, said process employing a tool comprising a positive molding surface for forming the negative molding surface of the plastic molds, the plastic molds being injection molded from the tool, the improvement wherein the tool is constructed of an engineering plastic resin that can withstand injection molding conditions and comprises an optically smooth molding surface, and wherein the shape of said tool molding surface substantially corresponds to a desired shape of a contact lens surface. 
     
     
       2. The process of claim 1, wherein the molding surface of said tool is convex. 
     
     
       3. The process of claim 1, wherein the molding surface of said tool is concave. 
     
     
       4. The process of claim 1, wherein the molding surface of said tool comprises a central zone having a first curvature and a peripheral zone having a second curvature different from said first curvature. 
     
     
       5. The process of claim 1, wherein the molding surface of said tool is spherical. 
     
     
       6. The process of claim 1, wherein the molding surface of said tool is toric.